PREPARATION OF OPTICALLY-ACTIVE AZOPHENOLIC CROWN-ETHERS CONTAINING 1-PHENYLETHANE-1,2-DIOL AND 2,4-DIMETHYL-3-OXAPENTANE-1,5-DIOL AS A CHIRAL SUBUNIT - TEMPERATURE-DEPENDENT ENANTIOMER SELECTIVITY IN THE COMPLEXATION WITH CHIRAL AMINES

With (2S,4S)-2,4-dimethyl-3-oxapentane-1,5-diol and (S)- or (R)-1-phen ylethane-1,2-diol as chiral subunits, optically active azophenolic cro wn ethers (S,S,S,S)-1, (R,S,S,)-2 (S,S,S,S)-3 and (R,S,S,R)-4 possessi ng two phenyl and two methyl substituents together with the p-(2,4-din itrophenylazo)phenol moiety have been prepared in enantiomerically pur e forms, Temperature-dependent enantiomer selectivity in the complexat ion of these crown ethers with chiral amines has been studied by the U V-visible spectroscopic method in chloroform and from the observed ass ociation constants, thermodynamic parameters for the complexation have been calculated.